Tech Corner: Building Custom Seat Mounts

You’ve successfully conquered the installation of an overdrive transmission that left you making a new transmission tunnel. You’ve performed an engine swap that challenged and required you to think critically outside of the box. And you’ve set yourself up with a custom array of gauges when the directions left you guessing and probing until you got them to work just right. The point? You know that there’s no shortage of obstacles when it comes to a project car. And you know that many of the installation processes are easier said than done. But you may not know that a task as seemingly straightforward as building custom seat mounts can catch you off guard.

Many situations could require seat mount fabrication for a hot rod. Maybe the stock seats are beyond saving, or maybe you just want to update the safety and comfort factors. Or perhaps the current seats simply don’t match your vision for the overhaul. In a budget build, you can always pull seats from another car. And if funds are particularly tight, you may want to use materials that you already have on hand to build the brackets, rather than buying them. But if you’ve committed to building the seats from scratch, you might have to make brackets specific for your application. Regardless of the scenario, it’s not that uncommon to have no choice other than to fabricate.

Personally, I’ve always found it helpful to go into a job knowing what tools I will need beforehand. If I catch myself running all around the shop looking for things during the building process, it’s easy for me to lose sight of the task at hand.

To start, you’ll need some method to cut the materials to length and an angle grinder to help finish rough edges. You’ll also need to make holes in the brackets for hardware, so a standard power drill or even a drill press will be needed along with the appropriate bits. Lastly, this will require a welder and, honestly, I feel like a Lincoln welder is the best purchase for the DIY guys out there. But you certainly have the room to pick your poison, as long as you can lay a good strong weld in your brackets during the build.

Building Custom Seat Mounts: Time for Design

Once you have your tools and materials on hand, start mapping out the design. The first thing I like to do is get my measurements of the base of the seat itself. Then, take a look at the portion of the floor pan where the seat will be mounted. With the measurements you’ve taken from the base of the seat itself, you can map out the area you will be working with.

Remember, the seat will need to be mounted level, so you need to take a look at the layout of the floor. Any differences in the height of the floor pan will need to be taken into account for when you are designing your mounts. For example, one side of the bracket may need to be shorter to keep the seat sitting level, or all four corners of the bracket may have to sit at different heights. By looking at the floor pan and the base of the seat, you can gauge how the bracket will need to be shaped.

If you are swapping seats in place of the factory seats or seats that already were mounted to the vehicle properly, you can cheat a little (without sacrificing quality, of course). If the dimensions of the seats are similar, use the previous brackets as a guide to shape the new ones. You may not be able to follow the design exactly, but the old brackets will give you a rough idea.

Building Custom Seat Mounts: Cut and Weld

After the layout design has been configured, you can move to cutting up the materials and tack welding your brackets together. Before you permanently weld everything, test-fit the brackets by placing them in the vehicle with the seats to make sure everything sits level. If you are satisfied with the results, you can move to welding everything together. If not, go ahead and make the proper adjustments until you are ready to finish the brackets.

During this part of the process, be conscious of where your mounting hardware will be located. You want to make sure you pick an area where the hardware will hold the seats firmly in place. Additionally, make sure the location of the hardware is easy to access for wrenching. If you’re looking to make an aesthetically appealing set of brackets, take the time after the welds are in place to make sure everything is cleaned up nice and neat.

Building Custom Seat Mounts: Mounting Hardware

Since it’s unlikely that you’ll be permanently mounting your seat brackets with a weld, you need to consider the hardware being used. When it comes to mounting the seat to the floor, 3/8” grade 5 bolts will do the trick. Anything smaller may fail in the case of an accident and can result in separation. And in the case that you’re doing any sort of racing, it’s imperative you check the rule book of the organization to ensure you will pass tech inspection.

Mounting seat brackets is one of those jobs that will vary from application to application. No two will be built the same. Because of that, there is a major sense of accomplishment when you finish making the specific mounts you need. It will fuel your desire to learn new skills and take on new challenges. And, honestly, it’s one more thing you can tell your buddies you did to your car that they didn’t.